In dialysis machines, a dialysis liquid is prepared by dissolving a salt (bicarbonate) stored in a cartridge or by diluting a liquid concentrate with the addition of a liquid stored in a cartridge. The cartridge may be externally clamped in a special cartridge holder of the machine, via which the content of the cartridge is tapped in line with demand. This means that the cartridge holder usually has to fulfill two functions: the supporting of the cartridge as well as tapping the content of the cartridge.